How to Grow Autoflowering Cannabis Seeds

White Express - AC GeneticsGrowing autoflowering cannabis seeds does not differ greatly from growing the usual Cannabis sativa and Cannabis indica varieties. However, there are a few differences you will need to take into account.

Of course, most notably the life cycle of the plants are very different. Most autoflowering cannabis seeds will flower automatically after 17-20 days of growth, which makes them ready to harvest after 60-65 days, some up to 70-80 days. This in contrast with the sativas and indicas who need the entire spring and large part of the summer to grow, plus a flowering period of 6-12 weeks when the light is weaning.

There are of course certain circumstances which will allow autoflowering cannabis seeds to develop in the best way possible.


Hours of light

On the internet there are many different opinion on this matter, varying from 16 to 24 hours of light each day. We favour 18 hours a day. So from the beginning to the end of the life cycle it's 18/6.


Autoflowering cannabis seeds enjoy airy soil, relatively low on nutrients. Standard pot plant soil is not suitable for autoflowering cannabis seeds (actually, not for sativa's and indica's either, by the way...). It's much better to buy your soil at a specialized growshop. Always go for the ´Light´ mix.

If you want or need to mix your own soil, you could start with a simple basic recipe such as:

  • 3 parts compost
  • 3 parts peat moss
  • 2 part perlite, pre-wet
  • 1 part vermiculite, pre-wet


During the first 12-14 days you won't have to feed your plant anything but water. After this period you could start adding growth nutrients, the light type. Continue this until the plant has been flowering for a week. This will amount to about two weeks of giving growth nutrients. Flush well and then switch to flowering nutrients for about 4 weeks. Again, use the light type. About a week before harvesting you can stop giving nutrients.

And please remember, don't feed them too much. Commercial producers of plant nutrients tend to advise very high concentrations of nutrients for your plants. We usually use a lot less, especially with autoflowering cannabis strains. If the bottle reads 20-30 ml per litre, we will use 10-20 ml per litre.

Size Of Pots

Most autoflowering cannabis seeds will not become very large. So really large pots are not advised to use. You could use pots varying in content from 3 - 15 litre. The larger the pot is you use, the more roots the plant will make, the higher and larger your plant will be. Of course there's a limit there. In our experience with most autoflowering cannabis seeds 15 litres pots are the limit. Every extra space it gets is basically useless. It doesn't harm your plants either by the way.


The outdoor grower is of course dependent on the time of the year. With autoflowering cannabis seeds you can start the germination when the first serious signs of  ´nice weather´ have come in spring. Of course it's important to take into account where you are situated, on this globe. In the warmer regions you could start early may. But if you live in a colder area you will need to wait a few weeks. During a long and warm summer you are able to start a new cycle of plants in the start of august. 2 to 3 cultivations are possible within one season!

In the somewhat colder regions it's most likely your autoflowering cannabis plants will need a few days more to fully mature than the amount of days given by the seed producer.

P.S. There are areas on this globe were during the summer the sun doesn't set at all, giving (nearly) 24 hours of daylight. The introduction of autoflowering cannabis seeds has enabled people in these areas to grow outdoors nowadays! From Finland to the North West Territories... Just give ´m a little bit of sun and they will thrive everywhere.

All info listed above is of course strain dependent, and as such could vary.


Submitted by visitor (not verified) on
actually i think you'll find all smokers are ALWAYS welcome EVERYWHERE. both your opinions are stupid anyway. just find a nice patch of land in the south of spain and grow away to your hearts content every sativa and indica you can possibly imagine. i just stick auto flowering seeds in to fill the voids until the REAL crop comes up trumps in october. auto's are just a good solution to a very small problem, one that doesn't affect me personally in the slightest.
Submitted by visitor (not verified) on
Hi Ive looked all over but still cant see any mention of re potting at any stage ????? should i pot these auto flowering seeds when cracked straight into 5L or bigger pots as i dont want to shock them. ............. Thanks in advance ;0)
Submitted by Bomba (not verified) on
For best results plant the newly germinated seeds directly into their final pots (1-2 gallon or 5-10 litres) and place them directly under 18 hour lights. Beware, smaller pots can result in smaller yields.
Submitted by visitor (not verified) on
doesnt effect you personally, thats why you posted a reply isnt it? lolol!!!!!!!!!!!
Submitted by dlschuch` (not verified) on
 both your opinions are stupid anyway. I am just curious.  Do you even smoke your product?  You are the most verbally aggressive toker I have ever read comments from.   When someone goes out of their way to create an info page complete with links pictures and formatting, the least you can do is comment courteously.  There is never a need for your type of response.  You give the rest of us a bad name. one that doesn't affect me personally in the slightest Or did you just come here to brag?  
Submitted by dlschuch` (not verified) on
 You comment"both your opinions are stupid anyway."     I am just curious.  Do you even smoke your product?  You are the most verbally aggressive toker I have ever read comments from.   When someone goes out of their way to create an info page complete with links pictures and formatting, the least you can do is comment courteously.  Have you ever created or been part of a blog?  One page can take days to complete if you are a professional like this person.  Even a bland vanilla blog takes time and effort. There is never a need for your type of response.  You give the rest of us partakers a bad name..   You comment" one that doesn't affect me personally in the slightest"             Or did you just come here to brag?  
Submitted by Sean leneghan (not verified) on
Hi I just started a low budget closet grow I have 5 autos going and have light and ventilation sorted I'm just wondering how often and how much to water my plants I have 2 12 ltr pots and 3 8 ltr I have started by spraying the soil with only water every 6 hours and I have 2 growing ATM 3 still germinating I have been told to spray for 3 weeks then start adding nutrients but how much do I water it by please quick as I'm worried I could be overwatering 
Submitted by visitor (not verified) on
Can You Clone them. Does it start over when new roots grow
Submitted by visitor (not verified) on
yes you can clone them, but no, they don't start over. So basically it's pointless to clone autoflowering plants.
Submitted by visitor (not verified) on
That comment is absurd. No, they don't start over as if from seed, but the clones do turn into a new plant that can also be cloned and so on. The clones mature and produce like any other plant. They are a clone of the mother and turn into another autoflower with the same cycle as it's parent.
Submitted by visitor (not verified) on
It's not an absurd comment, what he said was correct in a nut shell. They don't 'start over' because they have already started flowering. The advantage of clones from non-autoflowerers is they will go back in to veg stage, where these will not. So it isn't a good idea to clone them if you want a healthy plant you might as well start afresh.
Submitted by visitor (not verified) on
Cloning autos is stupid the cutting will not go into veg because there is very little if any on these plants. Also doing this you significantly reduce your yeild once again due to the whole no veg thing. There sole purpose is to be grown from seed without pruning "plants for idiots".
Submitted by visitor (not verified) on
I am growing Crtitical Autoflowering plants, I took 4 clones from them after about the fifth week and after they were already flowering, the clones I put under florescent light and the main plant is under a 600 watt hps , the main plant is about 4 foot tall and doing awesome light green like lime color and buds are tight and sticky smells awesome, the clones are about 1.5 foot tall and doing good they never stopped flowering. I will be putting the clones under the 600 watt hps light soon . so far these plants are awesome I expect quite a yield from the critical plants as they are packed with buds and the top is fat, this is one of the best autoflowering plants ive done yet, just make sure you take the clones early so they have time to grow as they wont stop flowering but will grow fast. love the auto flowering plants . my northern light/ big bud auto flowering plants are doing great also there almost done and the leaves are turning purple buds smell chronic and covered with snow , its about 4 foot tall and gonna be just tasty cant wait till its done and ready to smoke. get R done AUTOMATICALLY
Submitted by michael (not verified) on
Hey I also started auto northern light x big bud I have 1 in a hydroponic and 2 n soil just wondering how yours turned out I'm new at growing and would like suggestions if any thank you
Submitted by virginia gent on
I am about to finish my second auto grow and the info you supply is right on. I had a slight nute burn at the low rate they recomended. The other thing I have seen is that the yeild improves greatly if the plant is given 2-3 weeks longer (9-11) to mature.
Submitted by visitor (not verified) on
if u don't mind tell me what kind of light do u use please thru the whole phase steve
Submitted by visitor (not verified) on
Sorry, I'm not Steve, but I would like to answer the question. I would suggest a full spectrum, 4000 lumen or better, fluorescent, either tube or one that fits into a normal light bulb base for each square foot of growing space. This seems to work the best for me.
Submitted by visitor (not verified) on
Do they produce new seeds?
Submitted by John Dope on
Submitted by visitor (not verified) on
Can they be grown in a hydroponic system.
Submitted by visitor (not verified) on
can u use grow wool instead of soil?
Submitted by visitor (not verified) on
pubes on the gash
Submitted by visitor (not verified) on
cheese on the bell
Submitted by visitor (not verified) on
red or blue light for indoors?
Submitted by visitor (not verified) on
blue for veg and red for flower. Think of Metal halide as being blue and HPS being red.
Submitted by visitor (not verified) on
and do you have to move the lights as the plant grows??what do u think is the perfect distance?
Submitted by visitor (not verified) on
If I'm using a phototron, would it be best that I use autoflowering seeds or no?
Submitted by visitor (not verified) on
hey guys thanx for the article..any idea how much water do they need per day??
Submitted by visitor (not verified) on
I just recently bought auto flowering seeds and was going to start growing them in the back garden as the better weather is starting to come in, is this ok to go forward with? I was also looking to know how much I will get off these plants. This is also my first time at attempting to grow so any suggestions or advice would be much appreciated. Thanks
Submitted by visitor (not verified) on
If they have good light and soil and all of them flower fully, each plant should yield as much as 400-500 grams per plant.
Submitted by visitor (not verified) on
man im sorry but i have never heard of any autoflower plant yielding more than 90 grams and that was exceptional so a regular female will yield that much and thats a great grow.
Submitted by visitor (not verified) on
I am assuming the best light source for autos is LED, My question is what if it dont have a LED. Should I start under fluros and go to HPS once the signs of flower have come on? Do I just keep it under the same light source the whole time? Does changing it make any difference?
Submitted by visitor (not verified) on
Hi im just starting to grow autoflowering seeds for the first time and I'm wondering what i need to know about lights? I was told that it is possiable to use an energy saving light bulb instead of a iv lamp is this true? if not what am I meant to do? Any ways that wont affect the electricity bill too much?
Submitted by visitor (not verified) on
not unless your using a bunch of 1000 watt hps lights thats the only way it will affect your power bill what is best for a closet grow is 400 watt hps put a small fan in there so the air circulates.and mist them daily two or three times plain water they love humidity..goodluck
Submitted by visitor (not verified) on
hey is it at all possible to grow autoflowerig strains without nutrients and just normal soil just throw them in a pot and let them stand in a windowcounter ??
Submitted by visitor (not verified) on
I'd say that's unlikely to turn out well. They need a huge amount of light on a consistent basis, as well as a whole bunch of nutrients throughout their cycle - but why not have a go and tell us how it works out if you can afford to spare a seed on the experiment.
Submitted by visitor (not verified) on
I would have to agree and disagree with you the light is a major part and I'm on board what you said but you can plant them in soil no nute I am just pulling off some it is because there's already nute in the soil and the plant has such a short life that is doesn't drain the soil of everything but I wouldn't plant In that location again till I add more nutrients to the soil
Submitted by visitor (not verified) on
CAN SOMEONE PLEASE HELP!!!!!!! Ive been searching online for the best methods on growing auto flowering plants but there are a million answers that are all different..So i am asking a few simple probbaly stupid questions but i'm a new to this... I am using an 600W dimable 50 75 100 ballast and have both HPS and MH bulbs and am going with the 18/6 light cycle also using fox farm soil in 5 gallon buckets.... My Questions What light do i use first MH or HPS??? -OR- Do i just use one??? Do i need to switch the bulbs at any point during the plants growth cycle??? What percent of power do i use from the ballast from start to finish??? How far should the light stay from the plant as its growing??? thanks Mr.618
Submitted by visitor (not verified) on
the halide light is not really needed the hps is all you really need at least 400watt you dont want your plants outgrowing your growroom remember you will need atleast 8 weeks at 12-12 to flower them they will still grow vertical so make sure you will have room for the tops you should top them before you flower by doing this you will cut back on vertical growth and it should get bushy more bud areas...
Submitted by visitor (not verified) on
hey man, I really hope you can take the time to answer me on these two doubts. Im about to plant five feminised auto sweet tooth. I plan to use a sodium bulb the vege as well as flower periode. how many watts should I aet up? aælso, you talk about flushing well after changing nutes, what exactly does that mean? I plain down dont understandit. do I change the soil and wash their roots? looking forward for your answer!!
Submitted by visitor (not verified) on
A 400 or 600 watt light will be all you need. Good heavens, by no means should you wash the roots! Flushing the plants simply involves running water through the soil till in runs out the bottom. Use room temperature water and a volume at least equal to the size pot your plant is growing in i.e. a 3 gallon pot would be flushed with 3 gallons of water.
Submitted by visitor (not verified) on
no man no need to change soil and wash roots that would shock the plant at this stage by flushing just use about a half gallon water a day per plant for the last week to remove all chemicals.thats flushing when u switch from veg to bloom plain water for about a week. the last week before harvest water hard to remove all traces of nutes.
Submitted by yuli (not verified) on
SOS SOS !! I NEED HELP! we get over the germination part and after that i put it in drain well soil. it's not a big pot. and today is our 3 day in a pot. still no action. adn I DON'T KNOW WHEN I'M GOING TO START FOR THE LIGHT. so can anyone please contact me and help me.. i'm sorry for this retardedness but it's my first time if anyone writes the directions for this little new girl i would really appreciate..   [Edit by webmaster: No publishing of email addresses, please... And it's day 3. Don't worry, be patient]
Submitted by dbeck (not verified) on
will a 400w hps light be fine for growing ak47 auto all the way through  
Submitted by The Daily Smoker on

Yes, no problem...

Submitted by jay (not verified) on
Should you prune  autos iam doing black cream in soil and big devils xl , 4week old and budding but very bushy , and ther under 400hps what should I expected  from them ...Please help cause there's not a lot of information on them .Thanks
Submitted by chris (not verified) on
is it possable to grow autoflower with just household 100w bulbs?  
Submitted by greengo1888 (not verified) on
hi need some help just started auto grow useing 10litre pots want to no how much water it takes and what kind ov feed to i use and how much thanks
Submitted by droday (not verified) on
in my grow i have one Chocolate Kush off to the side under 1000w. hps light on 12/12/, its in a 10 gallon tub in perfect conditions, and mixd with special nutrients. but its doing amazing! a little over 5 ft. looking to yield atleast close to 3/4 of pound of wet weight! great plant. deff will grow again..very pest and mold resistent as well.    
Submitted by Mark Maystone (not verified) on
Hi can u start seed in rock wool or would that affect yield thanks